Catalyst Game Labs, the current owners of BattleTech, have divided history into eras and sub-eras. The products they release are grouped in this manner.. To reflect how the 1,000 lightyear separation between the Inner Sphere and the Clans renders Inner Sphere-centric era titles meaningless, Catalyst created a concurrent but disparate Clan Homeworlds Era in 2021.
|Pre-Star League||Pre-Spaceflight||Before 1950||Earliest era referenced - when humanity only resides on its planet of origin, Terra.|
|Early Spaceflight||1950 – 2005||Early spaceflight, restricted to the bounds of Sol. Notable events include the Second Cold War and reestablished Soviet Union.|
|Star League||Age of War||2005 – 2570||The era of the Terran Alliance, the colonization of the Inner Sphere, the formation of the Great Houses, and the Age of War.
KF Drive tech is introduced, beginning the First Terran Exodus in the 22nd century. In 2235 unrest sparks the Outer Reaches Rebellion, the Alliance loses and issues the Demarcation Declaration, setting most colonies free and sparking the Second Terran Exodus. Throughout the 23rd and 24th centuries the first independent interstellar nations are founded throughout the Inner Sphere, and the Periphery is settled.
The Alliance transforms into the more powerful Terran Hegemony and the Great Houses forge their own empires as neo-feudalism becomes dominant. The Age of War begins in 2398 and will last until the mid-26th century.
|Star League||2571 – 2780||The time of the First Star League from its founding in 2571 to the fall of the usurper Amaris Empire in 2780.
For nearly two centuries humanity is united under a single government. Advancements in science and engineering backed by the greatest military in history uphold nearly two centuries of peace and prosperity across all settled worlds. Save for minor conflicts dubbed the Hidden Wars, the SLDF rarely sees true conflict until Periphery revolts break out in 2765.
These rebellions enable Stefan Amaris to destroy the Cameron dynasty and seize the Star League throne for himself, resulting in the Amaris Civil War. Although Aleksandr Kerensky and his SLDF ultimately defeat Amaris, the Hegemony and Star League are irreparably ruined.
|Succession Wars ||Early Succession Wars||2781 – 2900||The collapse of the Star League is followed by two devastating Succession Wars.
Following the Star League's dissolution Kerensky and most of the SLDF leave the Inner Sphere in 2784. Within two years the five Successor States are waging total war (including heavy usage of nuclear weapons), each aiming to restore the Star League with its own dynasty at its head. The resulting First and Second Succession Wars span three generations and result in the loss of billions of lives, hundreds of worlds depopulated, and much scientific knowledge lost.
ComStar emerges from the last surviving ministry of the Star League, and by the end of the era has become a pseudo-religious order. Establishing itself on Terra the outwardly neutral order utilizes its monopoly on interstellar communications to manipulate the ongoing wars for its own agenda.
Beginning in 2866, the Third Succession War reflects the general decay across the Inner Sphere as it is an ongoing state of low-level conflict involving small units and raids rather than large armies and massive offensives.
|Late Succession Wars – LosTech||2901 – 3019||With much of the Star League's knowledge gone, the Third Succession War continues.
Advanced technologies have been become LosTech, and in contrast to the preceding wars the Third Succession War is a constant low-intensity conflict throughout this period. Combat grows more ritualized and medieval amongst 'Mechs, with duels being fought between MechWarriors in an effort to preserve what technology remains.
|Late Succession Wars – Renaissance||3020 – 3049||The Third Succession War ends, House Steiner-Davion becomes the Inner Sphere's most powerful dynasty, and the Helm Memory Core is rediscovered, beginning a techno-industrial renaissance.
The status quo is upended with the marriage of Hanse Davion and Melissa Steiner and the resulting union of the Lyran Commonwealth and the Federated Suns. In the ensuing Fourth Succession War the Capellan Confederation is reduced to a rump state and the Draconis Combine suffers heavy losses.
As a result of his nation's defeats Theodore Kurita reforms the Combine military with ComStar's aid and grants independence to the Free Rasalhague Republic. His efforts ensure that the nascent Federated Commonwealth fails to win a similar victory against the Combine in the War of 3039, though it remains the overwhelmingly dominant state in the Inner Sphere. By 3049 a Fifth Succession War and/or House Steiner-Davion's re-establishment of the Star League seems likely.
The discovery of the Helm Memory Core in 3028, coupled with other scientific efforts, begins a technological renaissance during the next two decades. The Inner Sphere slowly begins climbing back towards Star League-era levels of technology.
|Clan Invasion ||3050 – 3061||Coreward of the Inner Sphere, a new faction strikes from the Deep Periphery in early 3050 and changes the Inner Sphere forever.
With superior weaponry, unique OmniMech designs and Elemental infantry, these “Clans” with their warriors genetically bred for war cut through all opposition. During this Operation REVIVAL the Draconis Combine and Lyran half of the Federated Commonwealth lose many worlds, while the Free Rasalhague Republic is almost subsumed entirely. Eventually these invaders' origins become known: they are the descendants of the Star League-in-Exile returned to reestablish the Star League.
In the climactic Battle of Tukayyid ComStar's military arm wins a victory and a truce which halts the invaders for fifteen years. The Successor States frantically upgrade their armies for the inevitable hostilities while the Clans seethe at the enforced peace. ComStar undergoes reforms aimed at secularizing the organization, but dissident zealots exile themselves and form the fanatical Word of Blake in response, later seizing Terra.
The next two major conflicts erupt in 3057. Clan Wolf wages the Refusal War against Clan Jade Falcon to prevent a resumption of the invasion. At the same time Operation GUERRERO results in the Free Worlds League and Capellan Confederation reclaiming worlds lost during the Fourth Succession War - and sundering the Federated Commonwealth when Katherine Steiner-Davion orchestrates the secession of the rechristened Lyran Alliance.
The Battle of Coventry in 3058 leads to the Successor States forging the Second Star League, with the express purpose of ending the Clan Invasion. They accomplish this when Operation BULLDOG and Task Force Serpent conclude with the annihilation of Clan Smoke Jaguar. After the reborn SLDF wins the Great Refusal, the other Clans agree to end the invasion permanently.
|Civil War ||3062 – 3067||While the Clan threat is ended, the new Star League does not herald a new era of peace but several wars within the Inner Sphere itself.
Taking advantage of the rift in the former Federated Commonwealth and his own realm's Xin Sheng movement, Chancellor Sun-Tzu Liao continues reclaiming former Capellan worlds. His efforts culminate in the Capellan-St. Ives War which ends with the re-absorption of the St. Ives Compact into the Confederation.
While Katherine Steiner-Davion secures the throne of the Davion-half of her parents' realm, her tyrannical rule and tensions within both states finally erupt in 3062. The five-year FedCom Civil War between Katherine's Loyalists and Victor Steiner-Davion's Allies intent on dethroning her ravages both realms and their militaries before Katherine is finally defeated.
Numerous smaller conflicts are fought around the Inner Sphere during this period, most of them derived from the larger civil war. The Jade Falcons attack the Lyran Alliance again, while the Draconis Combine finds itself mired in border wars with both Clan Ghost Bear and the FedCom's Draconis March.
During these years the Word of Blake expands its power base outward from Terra, as well as building up its military might. Dismissing the fanatics as posing little danger, the rest of the Inner Sphere does not interfere.
|Jihad ||3068 – 3080 ||The Second Star League dissolves, prompting the Word of Blake to begin a Jihad that engulfs the entire Inner Sphere.
Acknowledging that the weak Second Star League is now purposeless, its members vote to end its existence. The Blakists impulsively react to the news by attacking Tharkad and New Avalon, beginning a war that eventually pits the Word against the rest of the Inner Sphere. The Blakists also target other capitals and important industrial worlds, create a "white-out" of the HPG network that adds to the chaos, and using their "hidden" armies carve out a Protectorate at the heart of the Inner Sphere.
Multiple border wars erupt elsewhere in the Inner Sphere, and the Draconis Combine is savaged by a three-way conflict involving the Blakists, the rebel Black Dragons and Kuritan loyalists. The Captain-General of the Free Worlds League, Thomas Marik, is exposed as an imposter, destabilizing the League and leading to its fragmentation in 3079. The Invading Clans become embroiled in the Wars of Reaving that sunder them from the Homeworlds before joining in the fight against the Blakists.
Eventually a coalition of nearly every major power in the Inner Sphere forms under the leadership of the mysterious Devlin Stone. Stone and his allies crush the Blakists and liberate their conquered worlds, but the Inner Sphere has suffered massive industrial and military damage, and entire worlds have been rendered uninhabitable.
|Dark Age ||Republic||3081 – 3130 ||Devlin Stone's reforms usher in a new era of peace as the Inner Sphere rebuilds after the Jihad.
Following the Word of Blake's defeat by Stone's Coalition, Devlin Stone and David Lear form the Republic of the Sphere from the liberated worlds of the Word of Blake Protectorate. This new power at the center of the Inner Sphere leads a disarmament program that decommissions BattleMechs and other tools of warfare, downsizes armies and removes any such material from the hands of private individuals. Stone and Lear attempt to build a new kind of nation, with the Republic home to citizens originating from all major Houses and Clans.
While raiding and some small-scale wars occur during this time, the overall state of affairs throughout the Inner Sphere is one of peace. Devlin Stone disappears in 3130 but his ideals are expected to continue upholding the status quo.
|Dark Age||3131 - 3150 ||The the collapse of the HPG network opens a new age of war with massive changes to the Inner Sphere.
The chaos in the Republic of the Sphere arising from the HPG Blackout leads to the militarization of Industrial Mechs and other civilian equipment, as different splinter factions fight to advance their own agendas. The Great Houses and the Clans attack the Republic and each other, with wars engulfing the entire Inner Sphere by the mid-3130s.
The Republic's core systems isolate themselves via the Wall, an impenetrable barrier to JumpShips, with the remaining Republic worlds abandoned to its neighbors. The Lyran Commonwealth invades the former Free Worlds League along with Clan Wolf, which abandons its occupation zone to migrate en masse farther into the Inner Sphere. The League's former members reunite in 3139, while the Wolves turn on their allies and carve out the Wolf Empire from its new conquests. Clan Jade Falcon falls under the leadership of Malvina Hazen, with her Mongol Doctrine of terror warfare. The Lyran Commonwealth survives constant attacks from the Wolf Empire and Jade Falcons but is left severely weakened.
The Draconis Combine undergoes a civil war ending in the annihilation of Clan Nova Cat, following which it mounts an all-out invasion of the Federated Suns that culminates with the fall of New Avalon. Attacked by the Capellan Confederation as well, the Federated Suns manages to avoid total destruction but is left on the brink of collapse.
Devlin Stone emerges from cryogenic storage to resume control of the Republic, and drops the Wall in 3149 to unleash new forces upon the Republic's enemies. But despite some setbacks both Clans Wolf and Jade Falcon position themselves right on Terra's doorstep, ready to claim humanity's homeworld.
|ilClan||ilClan||3151 – Present ||The once-invulnerable Republic of the Sphere lies in ruins, torn apart by the Great Houses and the Clans as they wage war against each other on a scale not seen in nearly a century Mercenaries flourish once more, selling their might to the highest bidder. As Fortress Republic collapses, the Clans race toward Terra to claim their long-denied birthright and create a supreme authority that will fulfill the dream of Aleksandr Kerensky and rule the Inner Sphere by any means necessary: the ilClan|
|Clan Homeworlds||Clan Homeworlds||2786 – Present||In 2784 General Aleksandr Kerensky launched Operation Exodus, and led most of the Star League Defense Force out of the Inner Sphere in search of a new world, far away from the strife of the Great Houses. After more than two years and thousands of light years, they arrived at the Pentagon Worlds. Over the next two-and-a-half centuries, internal dissent and civil war led to the creation of a brutal new society—the Clans. And in 3049, they returned to the Inner Sphere with one goal—the complete conquest of the Great Houses.|
- New to Battletech? - BattleTech Eras
- Heretic's Faith (2021 Edition), "BattleTech Eras"
- New to Battletech? - BattleTech Eras - Star League
- New to Battletech? - BattleTech Eras - Succession Wars
- New to Battletech? - BattleTech Eras - Clan Invasion
- New to Battletech? - BattleTech Eras - Civil War
- New to Battletech? - BattleTech Eras - Jihad
- New to Battletech? - BattleTech Eras - Dark Age
- Record Sheets: Clan Invasion, p. 4: "Battletech Eras"
- Blake Ascending: A Jihad Compilation
- Era Digest: Age of War
- Era Report: 2750
- Field Manual: 3085
- Field Manual: 3145
- Field Manual: Crusader Clans
- Field Manual: SLDF
- Field Manual: Updates
- Field Manual: Warden Clans
- First Succession War (Sourcebook)
- Handbook: House Davion
- Handbook: House Kurita
- Handbook: House Liao
- Handbook: House Marik
- Handbook: House Steiner
- Handbook: Major Periphery States
- Historical: Liberation of Terra Volume 1
- Historical: Liberation of Terra Volume 2
- Historical: Operation Klondike
- Second Succession War (Sourcebook)